SON Cavity Formation Using Decomposable Trench Fill and Epitaxy
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Solution Overview
Problem
Conventional SON device fabrication processes are complicated, necessitating a simpler method for forming the hollow cavity in silicon-on-nothing (SON) devices.
Innovation Solution
A method involving forming a trench in a semiconductor substrate, lining it with a dielectric layer, filling it with a decomposable material, growing an epitaxial layer, and vaporizing the decomposable material to form a cavity, simplifying the fabrication process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional SON device fabrication processes are used, then the hollow cavity can be formed, but the fabrication process becomes complicated
Solution Approach 1:
The fabrication process is divided into distinct sequential steps: forming a trench in the substrate, depositing a dielectric layer to line the trench, filling the trench with decomposable material, etching back to expose sidewalls, performing epitaxial growth to form the cavity wall, and finally vaporizing the decomposable material to create the hollow cavity. This segmentation allows each step to be optimized independently while simplifying the overall process control.
Solution Approach 2:
The decomposable material is deposited into the trench before the epitaxial growth step, serving as a preliminary structure that defines the future cavity shape. This preliminary action allows the cavity geometry to be pre-determined by the decomposable material layer, simplifying subsequent processing steps.
2Ease of manufacture
If the decomposable material layer is vaporized away after epitaxial layer formation, then the cavity formation is simplified, but the process requires precise sequencing
Solution Approach 1:
The decomposable material is deposited in advance before epitaxial growth, creating a template that defines the cavity geometry. This preliminary deposition simplifies the overall manufacturing by pre-establishing the cavity shape, reducing the complexity of subsequent cavity formation steps.
Solution Approach 2:
The decomposable material undergoes a phase transition from solid to vapor during the vaporization step, which occurs after the epitaxial layer has formed around it. This phase transition efficiently removes the temporary structure without affecting the newly formed epitaxial cavity wall, simplifying the cavity formation process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method allows for the formation of a cavity in a more straightforward manner, enhancing the performance of SON devices by suppressing drain-induced barrier lowering (DIBL) effects.
Implementation Method 1
forming a cavity by vaporizing away a remaining portion of the decomposable material layer along the gap
Implementation Method 2
performing an epitaxial growth process to grow an epitaxial layer on the exposed portions of the first sidewalls
Data Source
AI summary
A silicon-on-nothing (SON) device and a method for fabricating the SON device are disclosed. The method includes: providing a semiconductor substrate; forming a trench in the semiconductor substrate, the trench having first and second sidewalls; forming a dielectric layer lining the trench and covering a surface of the semiconductor substrate, the dielectric layer comprising stacked first and second dielectric layers; filling the trench with a decomposable material layer; etching back the decomposable material to remove portions of the decomposable material and the dielectric layer on the first sidewalls, exposing portions of the first sidewalls; performing an epitaxial growth process to grow, on the exposed first sidewalls, an epitaxial layer which completely fills the trench; removing the second dielectric layer using a wet etching process, forming a gap extending along the second sidewalls of the trench; and vaporizing away the remaining decomposable material layer along the gap, thereby forming a cavity.